This invention relates to a system incorporating retorting apparatus for ex situ processing of comminuted oil shale and other oil-yielding solid particulate materials to recover petroleum-like products therefrom.
Prior art systems for the extraction of oil from oil bearing solids have not in general been directed to the use of acetic acid in the process of operation thereof although the use of acetic acid for such purposes has been mentioned more to the negative than the positive aspects thereof. See Kimberlin et al., U.S. Pat. No. 2,966,450. The heating of solids in a retort by indirect heat exchange with a hot fluid also is not conventional.
U.S. Pat. Nos. 2,694,037 (Johnson et al.) and 4,058,205 (Reed) each disclose helical screw-type conveyors for moving fresh shale to a mixer or other treating apparatus. Reed discloses a preheater for preheating coal and shale immediately downstream of the first conveyor. U.S. Pat. No. 52,283 and U.S. Pat. Nos. 52,284 (Gengembre) and 2,073,367 (Fisher) all disclose a rotating shaft with stirring fingers that agitate material inside a cylindrical vessel. In the two Gengembre patents, the cylindrical vessel disclosed is of the retort type. U.S. Pat. No. 2,701,787 (Hemminger et al.) discloses a shale retort with a burner section in which the shale itself is burned. U.S. Pat. No. 4,104,537 (McQuitty) and U.S. Pat. No. 4,107,029 (Lorenz) each disclose a scraper at the bottom of a cylindrical vessel adapted to treat aqueous suspensions or slurries of tar sands or the like. U.S. Pat. No. 4,110,194 (Peterson et al.) and U.S. Pat. No. 4,189,376 (Mitchell) both disclose helical screw type conveyors for removing used particulate solids from the bottom of a treatment vessel. Peterson also discloses stirring fingers. Mitchell discloses means for injecting steam and solvent into different zones of the extraction vessel.
The system of the instant invention as aforementioned envisions a continuously operative system wherein crushed coal, oil shale, oil sands, wood, peat or the like are dumped from a dump truck into a receiving hopper for conveyance to a storage bin, from which bin it is then fed by an auger-type screw conveyor into the retort or silo where the separation process is effected. The apparatus incorporates inlets for acetic acid for use in the extraction process at the initial mixing and conveying stage as well as at at least one additional downstream location along the lower portion of a vertically oriented retort silo to provide for this introduction of additional acetic acid at an additional predetermined zone in the interior of the retort. Separation and continuous or periodic removal of the end products of the process together with the functioning of closed circuit systems for heat control, efficient use of hot gas, and use of steam both for heating and the admixing of acetic acid, facilitate the continuous operational nature of the apparatus.
It is a feature of the instant invention to provide a continuous retort system wherein a stream of solid particulate oil bearing or oil producing raw material is introduced into the top of a retort or silo reaction chamber where it is heated to successively higher temperatures, treated with steam and acted upon by acetic acid until petroleum-like oil products separate therefrom by volatilization into a gaseous mixture from which water and gaseous by-products are thereafter separated therefrom and solid waste material is removed from the lowermost portion of the retort.
It is an object of the invention to provide a continuously operable retort apparatus for obtaining petroleum-like products from shale or other oil-producing carbonaceous solids in a manner wherein the solid material from whence the oil products are desired to be extracted are subjected to a plurality of zones of increasingly varying temperatures as the solid products are mixed and conveyed through the retort apparatus towards the discharge outlet thereof.
In correlation with the foregoing object, it is a further object of the instant invention to incorporate in the heating in the system) heat exchange means which is provided for control of the temperature about the periphery of the material contained in the retort and which advantageously incorporates inlet and outlet ports, respectively, for the reception within the retort of gases utilized for heat transfer in the separation process and effective recovery and exhaust of hot spent gas for economical and highly efficient heat recirculation purposes.
It is a further object of the instant invention in correlation with the foregoing objects to provide agitation means within the retort or silo structure to facilitate mixing acetic acid and steam with the solid particulate material therein and for the prevention of caking of the solid particulate material as it moves through the retort by gravity.
Another object of the invention resides in the provision, in a continuously operable retort apparatus, of means for the introduction of acetic acid for enhancement of the yield of petroleum-like products from shale or other oil bearing or oil producing carbonaceous solids.
In correlation with the foregoing object, it is a further object of the instant invention to incorporate in conjunction with the steam and acetic acid introduction system, heat exchanger means for the control of the temperature within the retort which advantageously incorporates heat exchangers at the solids inlet and outlet ports.
Another object of this invention is the provision of a continuous running retort apparatus which includes means for the prevention of caking of the particulate material on the inner wall of the retort. Other advantageous benefits reside in the non-polluting character of the apparatus and the higher yields of oil than conventional retorting systems.
A still further object of the instant invention is to provide an environmentally acceptable system for the production of oil products from oil bearing and other oil producing carbonaceous solid materials.
A further object resides in the provision of a continuous-running trouble-free silo system in which the material to be processes is heated gradually so that the oil products are discharged from the retort as they are formed and are not decomposed by excessive heating after they are formed.